1. Field of Invention
This invention relates to radar cross section reduction in vehicles including aircraft, submarines, warships, tanks, troop carriers, and mobile weapons, and reduction of electromagnetic (EM) interference from civil engineering structures including bridges, buildings, power lines, and antennas.
2. Description of Prior Art
EM absorbers are often add-ons giving vehicles parasitic (contributing neither to structure nor aerodynamic performance) weight and drag, and degrading the flight performance of vehicles.
Salisbury Screens, Dallenbach Layers, and Multilayered Treatments are high volume treatments that are rendered ineffective by surface water from waves or weather. This limits effectiveness when deployed in inclement weather and marine environments. High-volume treatments cannot be deployed in volume-limited situations. Nuclear, biological and chemical (NBC) effects on the spacing materials deteriorate long term performance of high volume treatments in tropical, marine, chemical warfare, and nuclear battlefield environments.
Resistance cards and artificial dielectrics are subject to NBC effects on supporting materials. Resistance cards and artificial dielectrics cannot be deployed in volume-limited situations. Resistance cards and artificial dielectrics are of little use, and often are detrimental in bistatic scattering conditions. When scattering is out of the plane of the resistance card or artificial dielectric, it renders these treatments ineffective.
High-angle bistatic scattering renders high volume treatments, resistance card treatments, and artificial dielectric treatments ineffective against such problems as detection by certain surface-to-air missiles and phased array defense systems, and radio interference from civil engineering structures such as bridges, buildings, power lines, and antennas.
Magnetic Radar Absorbing Material (MAGRAM) is heavy, which limits vehicle ranges and degrades weight and balance envelopes. MAGRAM tends to be most effective at the low-frequency end of the radar spectrum, making MAGRAM ineffective against most targeting radars.
Shaping to reduce EM signature degrades aerodynamic performance and changes weight and balance in aircraft design.
Short life and poor erosion characteristics limit use of the above treatments on the forward sectors of propellers, rotors, and similar objects.
Low observable vehicles can make local air traffic control difficult in friendly air space.